A search for diamonds in Canada's far north turned up a rare fossil — a chunk of a redwood sealed in volcanic rock more than 50 million years ago.

A study of the well-preserved specimen, which also contains a sliver of amber, shows that the now-icy region where it was found had a swampier past.

The wood was found a few years ago in a kimberlite pipe, named the Panda pipe, over 1,000 feet (315 meters) below Earth's surface at the Ekati diamond mine, just south of the Arctic Circle in Canada's Northwest Territories, the researchers say. A kimberlite pipe, a type of volcanic pipe, forms when kimberlite magma pushes through deep fractures in the Earth's crust to create a vertical tubelike structure that's wider at the top like a carrot. Kimberlites have the deepest origins of all magmas on Earth and when they cool, they leave behind rocks dense in crystals, sometimes holding diamonds.

(Reuters) - Forget the diamond as big as the Ritz. This one's bigger than planet Earth.

Orbiting a star that is visible to the naked eye, astronomers have discovered a planet twice the size of our own made largely out of diamond.

The rocky planet, called '55 Cancri e', orbits a sun-like star in the constellation of Cancer and is moving so fast that a year there lasts a mere 18 hours.

Discovered by a U.S.-Franco research team, its radius is twice that of Earth's but it is much more dense with a mass eight times greater. It is also incredibly hot, with temperatures on its surface reaching 3,900 degrees Fahrenheit (1,648 Celsius).

"The surface of this planet is likely covered in graphite and diamond rather than water and granite," said Nikku Madhusudhan, the Yale researcher whose findings are due to be published in the journal Astrophysical Journal Letters.